High efficiency inspection of insulated pipes

Seeking for the most efficient way to inspect insulated pipes

With 3,500 NDT specialists, the global provider of nondestructive testing (NDT), inspection and related services Acuren offers the full spectrum of NDT/NDE methods. A major client encountered a weld root erosion issue associated with a mixed feed piping system. This system contains stainless steel piping of various outside diameters and most welds are insulated and at elevated temperatures.

Previous Ultrasound (UT) and conventional Radiographic (RT) inspections programs have been completed on the piping system with varying results. Hence, the client was looking for a more conclusive inspection program which could be used for a fitness for service calculation (FFS).

The problems with the current inspection techniques were as follows:

Manual Ultrasonic inspection

Removal of insulation in the welded area required causing additional costs

Safety issues due to high temperature of the uncoated pipes

Shearwave sound propagation required with second leg inspection for the weld root. This is a difficult task in thin wall piping and the results are operator dependent

No recordable data - no repeatability

Conventional film RT

Multiple exposures required on each weld, this process is time consuming with each film having to be processed in order to correct the technique for optimum film placement on the weld

Conventional film density is logarithmic which makes the calculation a mathematical equation. This process requires a highly trained individual

Radiation safety: the area has to be evacuated with large exclusion zones in place

Too time consuming and too large costs for the end result

In addition to the FFS issue listed above, the client was also looking for a cost effective, productive, quality and safe method of inspecting the piping system.

To meet the customer requirements, Digital Radiography performed with GE's portable wireless DXR 250 detectors utilizing the depth penetration tool for this inspection challenge along with the AcuView offsite analysis center in La Porte, Texas:

A local DR crew was mobilized to the client's site location. The crew had limited knowledge of the depth penetration software tool being utilized for the calculations performed by the image analysis experts in La Porte, but were highly trained on the DR technology, however the sole purpose of the crew was to maintain production rates which would make this a cost effective inspection program. Main advantages of this procedure are:

No insulation had to be removed as X-rays penetrate through it and this didn’t obstruct the calculations

Temperature of the piping was not an issue since the insulation was still in place

No film development time, this made the technique changes and alterations instantly achievable

Short exposure time which in turn limited the size of the radiographic exclusion zones

Continued production at site due to all images being wirelessly transmitted to the AcuView La Porte office

Acuren operates three AcuView centers, in Edmonton/Canada, Anchorage/Alaska and La Porte/Texas. By using GE’s Rhythm Enterprise Archive, a secure, DICONDE compliant data management system, digital inspection data completed in Europe, Alaska, Australia, the US Gulf coast or even offshore assets can be wirelessly uploaded and the images are reviewed by experts in any one of these three AcuView centers ... basically in real-time.

Faster, more reliable digital radiographic inspection

"It is a difficult question to quantify the productivity potential between conventional film inspection and digital radiography with instant inspection result review by AcuView NDT experts thousands of kilometers away," says Brian Anderson, Director of Applications Engineering at Acuren and adds: "But it is obvious that dramatic time and cost savings can be realized on multiple levels. For example, our current target for pipeline girth weld inspection with using DR as the primary inspection method is <1 hr downtime."

To evaluate efficiency, accuracy, repeatability and reproducibility of film (RT), computed (CR) and digital (DR) radiography in flaw location and sizing, Acuren has recently conducted a GAGE R&R study. As a result, RT showed lower accuracy ratings and was the most operator dependent method. CR with high resolution plates had most accurate results and least operator dependence, very closely followed by DR. However, when also taking inspection efficiency into account, DR performed with GE's DXR digital detector arrays becomes the preferred method as it is 50% faster than CR and even 71% faster than conventional RT:

• Customer focused. Provides small to large solutions from standalone workstation up to global enterprise network integration.

• Simplified information sharing. Data can now be readily accessed from a single storage source by any number of remote interrogation sites.

• Provides foundation for data mining. Ready access to large volumes of data at one central storage point allows operators to compare inspections carried out at different times using different inspection modalities.

• Robust and secure. Disaster-recovery plans are incorporated and built-in redundancy can be included to ensure constant data availability.

Since GE Oil & Gas has access to the full GE technology store, its customers exclusively benefit from advanced solutions developed in other GE businesses as well as GE's Global Research Centers (GRCs). E.g., the wireless DXR digital detector arrays used for this pipe inspection task have been developed at GE healthcare for medical use, but are optimized for industrial digital radiography in harsh environments. Also the Rhythm Enterprise Archive NDT data management and long-term storage system is based on GE Healthcare’s Centricity™, the world’s #1 software platform for archiving image based data in patient medical records.